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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Cristian Marussi <cristian.marussi@arm.com>,
	Dave Martin <Dave.Martin@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Will Deacon <will@kernel.org>, Sasha Levin <sashal@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH AUTOSEL 5.5 14/28] arm64: smp: fix smp_send_stop() behaviour
Date: Thu, 26 Mar 2020 19:23:43 -0400
Message-ID: <20200326232357.7516-14-sashal@kernel.org> (raw)
In-Reply-To: <20200326232357.7516-1-sashal@kernel.org>

From: Cristian Marussi <cristian.marussi@arm.com>

[ Upstream commit d0bab0c39e32d39a8c5cddca72e5b4a3059fe050 ]

On a system with only one CPU online, when another one CPU panics while
starting-up, smp_send_stop() will fail to send any STOP message to the
other already online core, resulting in a system still responsive and
alive at the end of the panic procedure.

[  186.700083] CPU3: shutdown
[  187.075462] CPU2: shutdown
[  187.162869] CPU1: shutdown
[  188.689998] ------------[ cut here ]------------
[  188.691645] kernel BUG at arch/arm64/kernel/cpufeature.c:886!
[  188.692079] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
[  188.692444] Modules linked in:
[  188.693031] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.6.0-rc4-00001-g338d25c35a98 #104
[  188.693175] Hardware name: Foundation-v8A (DT)
[  188.693492] pstate: 200001c5 (nzCv dAIF -PAN -UAO)
[  188.694183] pc : has_cpuid_feature+0xf0/0x348
[  188.694311] lr : verify_local_elf_hwcaps+0x84/0xe8
[  188.694410] sp : ffff800011b1bf60
[  188.694536] x29: ffff800011b1bf60 x28: 0000000000000000
[  188.694707] x27: 0000000000000000 x26: 0000000000000000
[  188.694801] x25: 0000000000000000 x24: ffff80001189a25c
[  188.694905] x23: 0000000000000000 x22: 0000000000000000
[  188.694996] x21: ffff8000114aa018 x20: ffff800011156a38
[  188.695089] x19: ffff800010c944a0 x18: 0000000000000004
[  188.695187] x17: 0000000000000000 x16: 0000000000000000
[  188.695280] x15: 0000249dbde5431e x14: 0262cbe497efa1fa
[  188.695371] x13: 0000000000000002 x12: 0000000000002592
[  188.695472] x11: 0000000000000080 x10: 00400032b5503510
[  188.695572] x9 : 0000000000000000 x8 : ffff800010c80204
[  188.695659] x7 : 00000000410fd0f0 x6 : 0000000000000001
[  188.695750] x5 : 00000000410fd0f0 x4 : 0000000000000000
[  188.695836] x3 : 0000000000000000 x2 : ffff8000100939d8
[  188.695919] x1 : 0000000000180420 x0 : 0000000000180480
[  188.696253] Call trace:
[  188.696410]  has_cpuid_feature+0xf0/0x348
[  188.696504]  verify_local_elf_hwcaps+0x84/0xe8
[  188.696591]  check_local_cpu_capabilities+0x44/0x128
[  188.696666]  secondary_start_kernel+0xf4/0x188
[  188.697150] Code: 52805001 72a00301 6b01001f 54000ec0 (d4210000)
[  188.698639] ---[ end trace 3f12ca47652f7b72 ]---
[  188.699160] Kernel panic - not syncing: Attempted to kill the idle task!
[  188.699546] Kernel Offset: disabled
[  188.699828] CPU features: 0x00004,20c02008
[  188.700012] Memory Limit: none
[  188.700538] ---[ end Kernel panic - not syncing: Attempted to kill the idle task! ]---

[root@arch ~]# echo Helo
Helo
[root@arch ~]# cat /proc/cpuinfo | grep proce
processor	: 0

Make smp_send_stop() account also for the online status of the calling CPU
while evaluating how many CPUs are effectively online: this way, the right
number of STOPs is sent, so enforcing a proper freeze of the system at the
end of panic even under the above conditions.

Fixes: 08e875c16a16c ("arm64: SMP support")
Reported-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/arm64/kernel/smp.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index d4ed9a19d8fe7..e4dc241c5a8e8 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -958,11 +958,22 @@ void tick_broadcast(const struct cpumask *mask)
 }
 #endif
 
+/*
+ * The number of CPUs online, not counting this CPU (which may not be
+ * fully online and so not counted in num_online_cpus()).
+ */
+static inline unsigned int num_other_online_cpus(void)
+{
+	unsigned int this_cpu_online = cpu_online(smp_processor_id());
+
+	return num_online_cpus() - this_cpu_online;
+}
+
 void smp_send_stop(void)
 {
 	unsigned long timeout;
 
-	if (num_online_cpus() > 1) {
+	if (num_other_online_cpus()) {
 		cpumask_t mask;
 
 		cpumask_copy(&mask, cpu_online_mask);
@@ -975,10 +986,10 @@ void smp_send_stop(void)
 
 	/* Wait up to one second for other CPUs to stop */
 	timeout = USEC_PER_SEC;
-	while (num_online_cpus() > 1 && timeout--)
+	while (num_other_online_cpus() && timeout--)
 		udelay(1);
 
-	if (num_online_cpus() > 1)
+	if (num_other_online_cpus())
 		pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
 			cpumask_pr_args(cpu_online_mask));
 
-- 
2.20.1


  parent reply index

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-26 23:23 [PATCH AUTOSEL 5.5 01/28] thunderbolt: Fix error code in tb_port_is_width_supported() Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 02/28] drm/bridge: dw-hdmi: fix AVI frame colorimetry Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 03/28] nvme-rdma: Avoid double freeing of async event data Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 04/28] ALSA: hda/realtek: Fix pop noise on ALC225 Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 05/28] staging: wfx: fix warning about freeing in-use mutex during device unregister Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 06/28] kconfig: introduce m32-flag and m64-flag Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 07/28] int128: fix __uint128_t compiler test in Kconfig Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 08/28] drm/amdgpu: add fbdev suspend/resume on gpu reset Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 09/28] drm/amd/display: Add link_rate quirk for Apple 15" MBP 2017 Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 10/28] drm/bochs: downgrade pci_request_region failure from error to warning Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 11/28] initramfs: restore default compression behavior Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 12/28] staging: greybus: loopback_test: fix potential path truncation Sasha Levin
2020-03-27  6:28   ` Greg KH
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 13/28] staging: greybus: loopback_test: fix potential path truncations Sasha Levin
2020-03-27  6:28   ` Greg Kroah-Hartman
2020-03-26 23:23 ` Sasha Levin [this message]
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 15/28] arm64: smp: fix crash_smp_send_stop() behaviour Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 16/28] modpost: Get proper section index by get_secindex() instead of st_shndx Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 17/28] drm/amdgpu: fix typo for vcn1 idle check Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 18/28] tools/power turbostat: Fix gcc build warnings Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 19/28] tools/power turbostat: Fix missing SYS_LPI counter on some Chromebooks Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 20/28] tools/power turbostat: Fix 32-bit capabilities warning Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 21/28] nvmet-tcp: set MSG_MORE only if we actually have more to send Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 22/28] btrfs: fix removal of raid[56|1c34} incompat flags after removing block group Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 23/28] kconfig: Add yes2modconfig and mod2yesconfig targets Sasha Levin
2020-03-26 23:41   ` Tetsuo Handa
2020-03-27  6:26   ` Greg KH
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 24/28] ALSA: pcm: oss: Avoid plugin buffer overflow Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 25/28] ALSA: line6: Fix endless MIDI read loop Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 26/28] ALSA: pcm: oss: Remove WARNING from snd_pcm_plug_alloc() checks Sasha Levin
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 27/28] tty: fix compat TIOCGSERIAL leaking uninitialized memory Sasha Levin
2020-03-27  6:27   ` Greg KH
2020-03-26 23:23 ` [PATCH AUTOSEL 5.5 28/28] drm/lease: fix WARNING in idr_destroy Sasha Levin

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